The present invention relates to battery chargers and, in particular, to chargers for switching a primary power source to charge a battery.
It is known to charge an automobile battery by means of a rectifier driven by a transformer whose primary is connected to the main alternating current line. These devices rely on the limited voltage producible by the transformer to limit the peak voltage applied to the automobile battery. A disadvantage with this type of system is that the need to supply relatively low voltage and current to avoid over-charging, causes rather long charging time. Attempts to increase the secondary voltage of these types of chargers results in excessive current being applied to the battery, particularly when it is fully charged.
It is also known to use a triac to switch an alternating current signal synchronously and at a varying duty cycle. By varying this duty cycle the triac can effectively regulate the power, voltage or current delivered from a power line.
Also known are ground fault detectors which sense the leakage current being carried by a ground wire. Such leakage current through a ground wire indicates a short circuit. Detection of this leakage current is used to operate a circuit breaker and remove power.
Accordingly, there is a need for a simple, efficient and safe device for quickly charging a battery.